How Many Babies Do Mice Have?

© ChristinLola/

Written by Kyle Glatz

Updated: October 10, 2022

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Some people keep mice as pets, while others use them to feed their reptiles of choice. Still, the majority of people see mice as pests. These rodents can sneak into your house, consume your food, leave droppings everywhere, chew through electrical wires, and cause all kinds of mayhem while they’re at it. The bad part is that these animals are very fast breeders with many babies. So, how many babies do mice have?

Let’s take a look at this issue, answer the question, and show you just how many baby mice a single creature can have in a year. You’ll see how a small problem can grow into a vast one in a very short amount of time.                

What is the Mouse Gestation Period?

baby mouse sleeping

Baby mice are born after three weeks of development.


Before we get into the number of babies that mice have at one time, it’s important to know how long they gestate. For example, a human’s gestation period is about 40 weeks or 280 days. That’s a rather long time.

However, the mouse’s gestation period is only between 19 and 21 days. Of course, there is some variation between species, but the average common house mouse needs just three weeks to give birth to its young.

Now, you may be thinking that mice have a cooldown period between pregnancies, right? The truth is that mice can get pregnant rather quickly after they have their litter, practically immediately in most cases. They can have an average of five and ten litters of mice per year!

You must also consider that a mouse reaches sexual maturity at about six weeks of age. That means new mice that are born can get pregnant and breed. You’re looking at a practically exponential breeding bonanza. So, just how many babies can you expect from a mouse at a single time?

How Many Babies Do Mice Have?

baby mouse closeup

Baby mice are rarely alone in a litter.

©Adrian Eugen Ciobaniuc/

Mice have between 6 and 8 babies per litter. When we add up the total number of litters they can have per year, mice can have between 30 and 70 babies per year. Of course, you’re rarely going to see a mouse that has so many babies. Yet, even if a mouse has 30 babies in a year, it’s not a good thing.

That means if you let a single pregnant mouse into your home, you could have a full-blown infestation develop between fall and spring. After all, mice have no qualms about inbreeding. So, six weeks after a litter of 8 babies, mice in your home could start breeding once again amongst themselves.

That means a month and a half after a litter is born, a new litter could be on the way in addition to the ones that have already invaded your home.

Of course, you do not have to suffer through a mouse infestation. You have a few options for what to do if you find mice in and around your home.

How Do I Know If I Have an Infestation?

baby mouse litter

A small litter or two can rapidly lead to an infestation in your home.

©Jennifer Thornhill/

We’ve answered, how many babies do mice have? By now, you’re probably worried about what could be living and breeding in your basement or garage. That’s why you’ll want to know how to spot an infestation of mice.  

Fortunately, mice are not very subtle creatures. If you have a mouse infestation in your home, you will know about it very quickly. Here are some of the signs that you have a mouse infestation:

For one thing, you may begin seeing clusters of small brown pellets. That’s mouse poop, and you do not want to touch it. Mouse poop can carry diseases that spread to people. You do not want to get sick, so be careful cleaning it up. More importantly, pay attention to where you found the droppings. You’ll need to pay attention to those areas for our next section.

You’ll often see torn-up bits of string, paper products, wool, cotton, and fiberglass in your home. Mice use these things for nests, so they often find and use them. If you start finding things like that strewn about your home, then you need to act fast. The mice are already inside and nesting.

Lastly, if you spot a mouse in your home, there’s a good chance they’re not just lost or visiting. You need to look for a nest. Moreover, you need to be proactive about their removal.  

What Should I Do if I Find Evidence of Mice?

A family of house mice eating spilled cereal off the floor

If you have one mouse in your house, you need to eliminate it before it leads to an infestation.


Once you have found some evidence of mice in or around your house, it’s time to take action. First off, you need to check your perimeters. Mice can climb walls and squeeze into very small spaces. As a result, you must examine the outside of your home. Find little holes or cracks where they could get in and block them with caulk, wire mesh, or other tough materials.

Next, use barrier methods outside your home like spraying peppermint oil around places where they get in or adding baited traps to keep them from getting into your home. Once you have figured out how to keep mice away from your house, you need to look closely at the inside of your home.

Do you see signs of nests? Are you finding droppings inside? Do you hear scurrying in the walls at night when mice are most active? If so, then you need to start setting traps and using poison pellets inside your home. Of course, you need to make sure that you’re using methods that are safe for your household. You don’t want to use traps or poison bait in areas where kids or pets can get them.

Following these steps can help stop an infestation before it gets too bad. However, once mice are in your home and reproducing, it will be harder to stop them.  

We’ve looked at the question and answers about how many babies do mice have? Unfortunately, it’s a lot. However, we’ve provided you with various ways to get rid of them. With this information in hand, you should have no problems solving the problem. Of course, if you have an infestation that you can’t solve, it may be time to call in the professionals. Have them come up with a specific plan to meet your needs.

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About the Author

Kyle Glatz is a writer at A-Z-Animals where his primary focus is on geography and mammals. Kyle has been writing for researching and writing about animals and numerous other topics for 10 years, and he holds a Bachelor's Degree in English and Education from Rowan University. A resident of New Jersey, Kyle enjoys reading, writing, and playing video games.

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